Understanding Fabric Shrinkage: Types and Causes

Shrinkage is a common issue in textiles, where a fabric’s dimensions decrease, causing the cloth to shrink from its original size either width-wise, length-wise, or both. This typically occurs during the washing process and can negatively impact the fit of garments, especially if the fabric has low dimensional stability. Cotton fabrics, in particular, are prone to two major drawbacks during washing: shrinking and wrinkling. Understanding the different types of fabric shrinkage can help in managing and mitigating these effects.

1. Constructional Shrinkage

Constructional shrinkage refers to the dimensional changes in a fabric that are entirely dependent on the construction factors used during the manufacturing process. When cotton fabric is created on a knitting machine or weaving loom, the yarn construction—such as the tightness of the weave or knit—determines the fabric’s intrinsic qualities. These qualities, present in the "greige delivered state" (the raw, unfinished state of the fabric), include its tendency to shrink. Constructional shrinkage is

measured at this stage and is influenced by how the fabric was constructed.

2. Relaxation Shrinkage

Relaxation shrinkage occurs due to the significant stresses that yarns, especially warp yarns, undergo during the weaving process. The weft (filler) yarns are also stretched, and these stresses can be temporarily "set" in the fabric during finishing processes like tendering and calendaring. When the fabric is soaked, it seeks to return to its natural, relaxed state, causing the yarns to contract and resulting in dimensional changes. This type of shrinkage is usually more pronounced in the warp direction but can also affect the weft direction, depending on the fabric.

3. Swelling Shrinkage

Swelling shrinkage happens when fibers in the fabric absorb water, causing them to swell. This swelling allows the yarns within the fabric to move more freely, especially in loosely woven fabrics, leading to a reduction in fabric size. As the fibers dry and lose water, they contract, further contributing to the overall shrinkage. The effect of swelling shrinkage is more significant in fabrics that are less tightly woven.

4. Felting Shrinkage

Felting shrinkage is primarily associated with fibers like wool that have a scaly surface structure. The frictional properties of these fibers cause them to move within the yarn or fabric structure during washing, leading to shrinkage. This type of shrinkage is particularly important in woolen fabrics, where the fibers interlock more tightly during washing, resulting in a smaller, denser fabric.

5. Processing Shrinkage

Processing shrinkage occurs in synthetic yarns and fabrics when they are exposed to temperatures above 210 °C. This high heat can cause the yarns to shorten, leading to shrinkage. However, synthetic fabrics that are heat-set during or after fabric formation can largely resist this tendency. Without heat-setting, synthetic yarns are prone to shrink when subjected to steaming or pressing during garment manufacturing.

Conclusion

Understanding the different types of shrinkage—constructional, relaxation, swelling, felting, and processing—is crucial for anyone working with textiles, especially in garment manufacturing. Each type of shrinkage has distinct causes and effects, and by recognizing these, steps can be taken to minimize their impact on the final product. Whether through careful selection of fabric, appropriate finishing processes, or controlled washing techniques, managing shrinkage is essential to ensure the quality and fit of garments.